Pneumatic sizer



Sept. 3o, 1924. 1,509,909

` v A. H. STEBBINS PNEUMATIC SIZEH Filed April 8, 1922 2 Sheets-Sheet 1 Sept. 3o, 1924.

A. H. STEBBINS PNEUMATIG SIZER 2 Sheets-Sheet 2 Filed April 8l 1922 /N VEN TfDR I l A. ATTORNEY Patented Sept. 30, 1924.

ALBERT H. STEBBINS, F LOS ANGELES, CALIFORNIA.

PNEUMATIC SIZER.

Application inea April a,

To all whom, it may concern Be it known lthat I, ALBERT H. STEBBiNs,\, a citizen of the United States, residing at Los Angeles, in the county of Los Angeles and State of California, have invented .an Improvement in Pneumatic Sizers, of which the following description, in connection with the accompanying drawings, is a speciication, like characters on the drawings representing like parts.

The present invention relates pneumatic sizers or se arators for separating materials in accor ance with their size and specific gravity. h

Heretofore the sizing of materials has been commonly accomplished by the use; of screens or screen cloth, the materials being delivered to the upper face of the screen so that the finer materials pass through the apertures of the screen out of engagement with the coarser materials.

In various fields of industry, and more particularly in the treatment of ores, it may be desirable to separate the materials in accordance with their size, and also to produce a partial classification of the materials in accordance with their di'erences in speciic gravity, to facilitate separation of the values from the foreign materials. This cannot be done by the ordinary screen or screening surface, because screens separate in accordance with size alone.

lIilie pneumatic sizers or separators of the present invention are constructed to cause air to pass through the materials to be separated as these materials travel along a supporting surface, and in separators of this type, it is important that the air currents passed through the supporting surface and the materials traveling over the surface, be of suilicient strength to carry ofi' the lighter articles of the materials while leaving the lieavier particles. It is therefore important that the air currents passing through different portions of the supporting surface be substantially uniform in strength.

In some cases it may be desirable eitherto decrease or increase along the supporting surface the strength of the air currents to which the materials are subjected as the materials progress along this surface, but the change in the strength of the air currents should be gradual, and local eddy current and other abnormal currents tending to 1922. Serial No. 550,873.

produce nonuniformity in thesseparating operation should be avoided. I

One important feature of the present invention therefore consists inmeans for effecting passage of air currents through the active area of a material supporting surface, and in means for controlling the air currents in accordance with the requirements of the separating operation.

Another important feature of the invention consists in a casing which is constructed to provide a separating chamber adjacent the material supporting surface and having walls converging from this chamber to increase the velocity-of the air as it leaves the chamber, thereby to arrest the discharge of materials from the air.

Another important feature of the invention consists in a unit sizer or separator provided with a plurality of material supporting surfaces and with a cooperating separating chamber for each of the surfaces.

Other features of the invention and novel combinations of parts will be hereinafter described in addition to the above, and in connection with the accompanying drawings which show' one good practical form of the invention, wherein:

Fig. 1 is a vertical central sectional view through a pneumatic sizer constructed in accordance with the present invention.

Fig. 2 is a front elevation of Fig. 1.

Fig. 3 is an enlarged sectional View taken on the line 3 3 of Fig. 1.

Fig. 4 is a front elevation of a pneumatic sizer unit embodying a plurality of the single sizers of Fig. 1.

Fig. 5 is an enlarged perspective view of a portion of the sizer unit o f Fig. 4: and

Fig. 6 is a perspective view of portion of an aperture, material supporting surface.

The pneumatic sizer shown comprises a casing l() mounted upon a supporting frame having front legs 11 and rear legs 12 connected by lower braces 13 and upper inclined braces 14.

.The materials to be separated or sized preferably are carriedV by gravity downwardly over an inclined surface 15 supported by the casing, and while passing over this surface are subjected to air currents passing through the surface. The inclined surface 15 preferably is provided with apertures to admit the passage of air upwardly therethrough and these apertures preferably are so constructed that they prevent the materials being separated from escaping there' through.

The casing 10 is shown as extending over the supporting surface 15 and is constructed to form a separating chamber adjacent the surface 15. The casing 10 is so constructed that it causes the air currents passing through the apertures of the surface 15 to be more or less uniform in strength, and to this end, in the present embodiment of the invention, the casing 10 is provided with substantially parallel walls 16 between which the surface 15 may be secured as shown in Fig. 3, and the walls 16 preferably form a chamber having substantially the width of the surface 15. At some distance from the surface 15 the walls 16 converge inwardly as at 17 to form a restricted throat orpassage 18 extending in the saine eneral direction as the surface 15. Be on the throat or passage 18 the walls are outwardly as at 19 to form a chamber 20 connected to an air discharge conduit 21. One end of the casing 10 is closed by a wall 22 and the other end is closed by the angularly disposed walls 23 and 24.

The casing 10 preferably is secured to the inclined braces 14 so that the apertured surface 15 and wall 22 are inclined substantially as shown. Materials are conveniently delivered to the upper end of the apertured surface 15 by a hopper 25 and the ow of materials may be Controied .by a Sliding gate 26 adjustable to vary7 the size of the discharge opening of the hopper.

In the construction shown, air currents are produced through the apertures of the surface 15 by producing a suction within the casing 10 and, to this end, the conduit 21 is connected to suitable air exhaust means. In certain applications of the invention however it may be desirable to force air through the apertures instead of sucking it through as in the present case. An adjustable gate 27 within the conduit 21 serves to control the air suction within the `casing 10.

The air currents passing through the apertures of the surface 15 will pick up the lighter particles of the materials carried downwardly by gravity over the surface, but will leave the heavier articles, and the latter will a from the ower end of the surface 15 into a discharge pipe 28 preferably having a trap 29 at its lower end adapted to permit the materials to escape without permitting air to enter. The liner materials picked up by the air currents will be carried into the se arating chamber between the walls 16 w ere Some of the materials will move downwardly and fall upon the inclined wall 22 while others will pass through the throat or passage 18 and be carried 0E by the air through the conduit 21. The materials deposited upon the inclined wall 22 in the se arating chamber or in the chamber 20 sli e downward into the pipe 28.

As stated, it is important that' the strength of the air currents passing through the apertures of the surface 15 be substanltially uniform, and the restricted throat orfassage 18 contributes materially to this en for it prevents an excessive flow of air from any one art of the surface 15 to the conduit 21. urthermore, should it be desired to produce air currents at one end of the surface 15 that are stron r than at the other end of the surface, this is readily accomplished by increasing the size of the passage 18 in a corresponding manner to permit a greater flow of air through one end of the passage than the other. This construction is shown in Fig. 3 wherein the walls of the passage taper slightly, so that the passage 18 is somewhat wider at its upper end than at its lower end, but in some cases it may be desired to construct the pas e so that it will taper in the op ite irection.

n the present construction the air chamber within the casing 10 extends from the surface 15 in a direction generally perpendicular to this surface, and the air currents within said chamber travel from the apertures in a direction to carry the lighter materials along paths forming a substantial angle with the direction in which gravity acts upon the materials. As a result the heavier particles within the air are moved by gravity out of the path of the air currents in a direction inclined to said ath. This is desirable because it causes the eavier particles moving downwardly by gravity through the air currents to cross the path of travel of the air currents so that they are subjected to a thorough cleaning action by the air.

It is desirable to maintain the width of the surface 15 within certain limits, since it is diicult to control the passage of air therethrough if the surface is too wide. This necessarily limits the amount of material that may be passed over a single surface 15 for separation, and it may therefore be desirable to provide a unit sizer or separator having a plurality of separating chambers each constructed in accordance with the disclosure of Figs. 1, 2 and 3. One form of this unit sizer or se arator is shown in Figs. 4 and 5 wherein our similar se arator casin 10 are arranged side by si e, it being un erstood however that the number of casings may be varied as desired. The several casings 10 may be supported by a frame similarto, but of greater .width than the frame of Fig. 1, and a single hopper 30 may supply materials to the several separating casings Likewise a single conduit 31 may serve to produce a suction in each of the casin s 10, and this conduit may be connected to t e casingsby branch tubes 32. An adjustable gate 33 1n the conduit 31 serves to control the air suction in the several casin s, and all the casings may discharge the eavier materials into the enlarged upper end 34 of the discharge pipe 35.7

One desirable 'construction of the apertureclsurface 15 is shown in Fig. 6 wherein the apertures face away from the direction in which the materials travel and the li s 36 extend upwardly to deflect the materia s from the apertures. The air currents entering the apertures will further assist in preventing the materials from escaping through the apertures. It is not necessary, however in all cases that the apertures 4face away from the direction in which the materials travel, as the air currents may be of suliicient strength to prevent the materials from passing t rough the apertures. f From the foregoing disclosure it will be seen that the neumatic sizer of the present invention is ree from moving parts that may get out of order, and that the air passing pward through the materials being treat will remove the dust and fine particles, but will leave the particles which due to their size or specific gravity cannot be picked up by the air provided. It will also e apprent that the capacit of a machine may increased as desire by increasing the number of single sizers providedin a pneumatic sizer unit.

What is claimed is: 1. A pneumatic sizer, comprising in combination, an inclined apertured surface, means for delivering'materials to .be separated to said surface, a casing forming a chamber extending over said surface, suction means for effecting passage of air currents through the apertures of the surface, and means for controlling the passage of air through said surface so that the strength of the a1r will be gradually decreased as the materials travel lengthwise of the surface, comprising a restricted throat within the casing extending approximately arallel to the surface and havlng the openlng'of the y throat gradually decreased in the direction of its lower end.

within said casing so that 2. A pneumatic sizer, comprising in combination, a steeply inclined apertured surface, means for delivering materials to be separated to said surface, a casing forming a chamber extending over said surface and -shaped to project from the surface in a direction generally perpendicular thereto, means for producing air currents Within said chamber that travel from the apertured surface in a direction that forms a substantial inclination with a vertical plane sothat the heavier particles that are picked up by the air currents will move across the path of the air under the action of gravity thoroughly to subject these particles to the action of the air, and means forming a slot-like throat for controlling the e strength/ of the air passing through different ortions of the apertured surface will be su stantially uniform.

3. A pneumatic sizer, comprising in combination, a casing provided with an apertured surface and forming a separating chamber above said surface, means for su porting the casing at an angle to incline t e apertured surface downwardly, means for delivering materials to be treated to the u per end of the apertured surface to sli e ownwardly over the surface, suction means for drawing ar into the casing through the apertures of the surface and materials thereupon, and means for controlling the passage o air through said surface, comprising a restricted slot-like throat within the casing above the .surface and extending approximatel parallel to the surface.

4. pneumatic sizer, comprising in combination, an apertured surface supported at a longitudinal inclination, a casing for said surface forming a se arating chamber above the surface, means or delivering materials to be treated to the up r end of the apertured surface to slide ownwardly over the surface, suction means for drawing a'ir into the casing through the a ertured surface and materials thereupon, an means for controlling the passage of air through said surface, comprising a restricted slot-like throat within the casing above the surface and tapered slightly from one end towardv the other.

In testimony whereof, I have signed my name to this specification.

ALBERT H. STEBBINS.

assage of air v i 

